Embodiments of the inventive concepts disclosed herein are directed generally to head-tracking systems and methods for automatically aligning components of a head-tracking system to a vehicular boresight or reference frame (a process generally referred to as “boresighting”). While generally associated with aircraft, boresighting may also apply to ground-based or seagoing vehicles. A head-tracking system may be utilized in a head-worn display (HWD) to provide enhanced situational awareness to the wearer (e.g., a pilot or crewmember). The head-tracking system may include a georeferenced inertial head-tracker (GHT) to determine the position and orientation of the wearer's head relative to the earth, and thereby accurately display imagery of the wearer's surroundings. The HWD may further generate and superimpose symbology on the displayed images to further augment scene content.
In order to meaningfully enhance situational awareness, the head-tracking system must be accurate and responsive (e.g., low-latency, high-rate refresh). Otherwise, displayed objects and features may not conform precisely to the real-world visible positions of those objects and features; for example, an object projected onto the combiner of an HWD may not align precisely with the actual, visible object. For example, the GHT may incorporate platform-referenced head tracking to determine the position and orientation of the wearer's head relative to the platform and thereby estimate the position and orientation of the head relative to the earth. For example, the inertial measurement units (IMU) of the GHT may be used for high frequency (e.g., >100 Hz) detection of head poses (pose including both a position and a relative orientation, e.g., of the head relative to the platform) as the head moves from instant to instant. An optical magnetic, or other absolute position/orientation sensing tracker (e.g., an optical head-tracker (OHT) or magnetic head-tracker (MHT)) may correct the GHT at a lower frequency by estimating head positions relative to the aircraft, using a series of optical markers (e.g., reflectors or light-emitting diodes (LEDs)) detectable by a helmet-mounted camera aligned with the user's head, or by a cockpit-mounted camera (wherein the optical markers are helmet-mounted). This requires that the optical markers be characterized and located in reference to the aircraft boresight, an expensive and time-consuming process.